Hydrophilic nonwoven fabrics are used in particular as nonwoven covering fabrics or as nonwoven intermediate fabrics in multi-layer nonwoven fabrics for sanitary products such as baby diapers, sanitary napkins, incontinence products and similar products. Such nonwoven fabrics function to quickly pass body fluids such as urine to the underlying absorption layer.
For producing the nonwoven covering fabrics, fibers or filaments of polyolefin or polyester are used in most cases. These polymers, however, are hydrophobic and therefore have to be hydrophilized either during production of the fiber and/or during the further processing into the nonwoven fabric. Hydrophilizing is usually performed by treating the filaments with known spinning preparations which are then processed further to form staple fibers and nonwoven fabrics. Also common is the treatment of the nonwoven fabrics with a hydrophilic finishing agent as a so-called “top coat” prior to the further processing into a sanitary product.
The treatment of the hydrophobic fibers, filaments or nonwoven fabrics with a hydrophilic spinning preparation or a hydrophilic finishing or dressing agent is intended to result in as long-lasting a hydrophilizing as possible, which is not or only to a minor degree washed out by fluids, and to provide the nonwoven fabric with as constant a hydrophilicity as possible over as long a period of its useful life as possible.
Such hydrophilizing compositions are known in the prior art. U.S. Pat. No. 4,988,449 describes hydrophilizing compositions which contain diethanol amides and non-ionic surfactants, alkyl phosphates, quaternary ammonium salts and/or alkyl imidazolium salts and are made use of as agents providing fluid permeability to polyolefin nonwovens.
U.S. Pat. No. 5,258,129 discloses hydrophilizing compositions which contain polyoxyalkylene-modified polydimethylsiloxanes alone or in combination with non-ionic surfactants, alkyl phosphates, quaternary ammonium salts and/or alkyl imidazolium salts.
EP 410 485 B1 discloses a method of hydrophilizing polyolefin fiber nonwovens by applying an aqueous mixture of alkoxylated surfactants to the surface of the fibers, wherein at least 80% of the composition consists of alkoxylated triglycerides of C18 fatty acids.
EP 0 839 947 A2 discloses hydrophilizing compositions that contain non-ionic surfactants in combination with a polyoxyalkylene-modified polydimethylsiloxane and/or a quaternary ammonium compound.
EP 1 600 532 B1 describes hydrophilizing compositions that consist of an alkoxylated glycerol esterified with a fatty acid and an alkoxylated or alkoxylated and hydrogenated ricinolein esterified with a fatty acid.
To increase the wearing comfort of incontinence products, it has already been proposed that the hydrophilic nonwoven covering fabrics arranged on the side facing the body be subsequently finished with hydrophobic care lotions on the diaper making machine. EP 1 671 609 B1 proposes applying the lotion in the form of a pattern of a plurality of stripes onto the surface, facing the body, of the nonwoven covering fabric, so that the nonwoven covering fabric can continue to fulfill its function of distribution of liquid.
WO 2012/047986 A2 describes a lotion for being applied to the nonwoven covering fabric of a sanitary product, the lotion being adjusted to be hydrophilic and comprising 0.1-90% of a microcrystalline wax, 0.1 to 25% by weight of a POE-4 monolaurate, 0.1 to 50% by weight of a POE-8 monostearate, and a carrier such as petrolatum.